000 WTPZ44 KNHC 200853 TCDEP4 HURRICANE DORA DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL EP042011 200 AM PDT WED JUL 20 2011 WHILE AN EYE HAS NOT BEEN APPARENT IN RECENT GEOSTATIONARY IMAGERY ...THERE HAS BEEN AN OVERALL INCREASE IN DEEP CONVECTION NEAR THE CENTER OF DORA IN THE PAST FEW HOURS. THE INITIAL INTENSITY IS SET TO 70 KT FOR THIS ADVISORY BASED ON A BLEND OF DVORAK ESTIMATES OF 77 KT FROM TAFB AND 65 KT FROM SAB AT 0600 UTC. DORA WILL BE IN AN ENVIRONMENT THAT IS VERY FAVORABLE FOR INTENSIFICATION OVER THE NEXT 36 TO 48 HOURS...WITH VERY WARM SSTS AND SHEAR OF AROUND 10 KT OR LESS. AFTER THAT TIME...DORA WILL MOVE ACROSS A SHARP SST GRADIENT INTO COOLER WATERS AND A MORE STABLE ATMOSPHERE...WHICH SHOULD RESULT IN RAPID WEAKENING LATE IN THE PERIOD. IN THE SHORT TERM THE OFFICIAL FORECAST LEANS TOWARD THE GFDL MODEL...AND SHOWS A PEAK INTENSITY OF 110 KT IN 36 HOURS. AFTER THAT TIME...THE NHC FORECAST IS CLOSEST TO A BLEND OF THE SHIPS AND LGEM. THE INITIAL MOTION ESTIMATE IS TOWARD THE WEST-NORTHWEST AT 16 KNOTS ...AS DORA CONTINUES TO BE STEERED BY THE STRONG MID-LEVEL RIDGE CENTERED OVER THE CENTRAL UNITED STATES. AS THE RIDGE WEAKENS AND MOVES EASTWARD OVER THE NEXT COUPLE OF DAYS...DORA WILL GRADUALLY SLOW DOWN AND TURN TOWARD THE NORTHWEST. MUCH OF THE TRACK GUIDANCE FOR THIS CYCLE HAS SHIFTED BACK TO THE LEFT...INCLUDING THE GFS...GFDL....AND HWRF MODELS. THE NEW OFFICIAL FORECAST HAS BEEN NUDGED TO THE LEFT AND LIES NEAR THE MULTI-MODEL CONSENSUS THROUGH 48 HOURS AND IS TO THE RIGHT OF THE CONSENSUS AFTER THAT TIME. GIVEN THE LARGE CYCLE-TO-CYCLE VARIABILITY IN THE TRACK GUIDANCE AND THE EXTENT OF 34-KT WINDS NORTH OF THE CENTER...THE TROPICAL STORM WATCH REMAINS IN PLACE FOR PART OF THE COAST OF MAINLAND MEXICO. BASED ON THE OFFICIAL FORECAST AND PAST NHC FORECAST ERRORS...THERE IS A 35 TO 40 PERCENT CHANCE OF TROPICAL STORM FORCE WINDS OCCURRING SOMEWHERE IN THE WATCH AREA. DORA COULD ALSO THREATEN THE SOUTHERN BAJA CALIFORNIA PENINSULA IN 60 TO 72 HOURS. FORECAST POSITIONS AND MAX WINDS INIT 20/0900Z 14.1N 101.6W 70 KT 80 MPH 12H 20/1800Z 15.1N 103.5W 85 KT 100 MPH 24H 21/0600Z 16.4N 105.5W 95 KT 110 MPH 36H 21/1800Z 17.5N 107.1W 110 KT 125 MPH 48H 22/0600Z 18.6N 108.4W 105 KT 120 MPH 72H 23/0600Z 20.5N 110.7W 85 KT 100 MPH 96H 24/0600Z 22.5N 113.5W 55 KT 65 MPH 120H 25/0600Z 24.0N 117.0W 30 KT 35 MPH $$ FORECASTER BRENNAN 000 WTPZ44 KNHC 200853 TCDEP4 HURRICANE DORA DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL EP042011 200 AM PDT WED JUL 20 2011 WHILE AN EYE HAS NOT BEEN APPARENT IN RECENT GEOSTATIONARY IMAGERY ...THERE HAS BEEN AN OVERALL INCREASE IN DEEP CONVECTION NEAR THE CENTER OF DORA IN THE PAST FEW HOURS. THE INITIAL INTENSITY IS SET TO 70 KT FOR THIS ADVISORY BASED ON A BLEND OF DVORAK ESTIMATES OF 77 KT FROM TAFB AND 65 KT FROM SAB AT 0600 UTC. DORA WILL BE IN AN ENVIRONMENT THAT IS VERY FAVORABLE FOR INTENSIFICATION OVER THE NEXT 36 TO 48 HOURS...WITH VERY WARM SSTS AND SHEAR OF AROUND 10 KT OR LESS. AFTER THAT TIME...DORA WILL MOVE ACROSS A SHARP SST GRADIENT INTO COOLER WATERS AND A MORE STABLE ATMOSPHERE...WHICH SHOULD RESULT IN RAPID WEAKENING LATE IN THE PERIOD. IN THE SHORT TERM THE OFFICIAL FORECAST LEANS TOWARD THE GFDL MODEL...AND SHOWS A PEAK INTENSITY OF 110 KT IN 36 HOURS. AFTER THAT TIME...THE NHC FORECAST IS CLOSEST TO A BLEND OF THE SHIPS AND LGEM. THE INITIAL MOTION ESTIMATE IS TOWARD THE WEST-NORTHWEST AT 16 KNOTS ...AS DORA CONTINUES TO BE STEERED BY THE STRONG MID-LEVEL RIDGE CENTERED OVER THE CENTRAL UNITED STATES. AS THE RIDGE WEAKENS AND MOVES EASTWARD OVER THE NEXT COUPLE OF DAYS...DORA WILL GRADUALLY SLOW DOWN AND TURN TOWARD THE NORTHWEST. MUCH OF THE TRACK GUIDANCE FOR THIS CYCLE HAS SHIFTED BACK TO THE LEFT...INCLUDING THE GFS...GFDL....AND HWRF MODELS. THE NEW OFFICIAL FORECAST HAS BEEN NUDGED TO THE LEFT AND LIES NEAR THE MULTI-MODEL CONSENSUS THROUGH 48 HOURS AND IS TO THE RIGHT OF THE CONSENSUS AFTER THAT TIME. GIVEN THE LARGE CYCLE-TO-CYCLE VARIABILITY IN THE TRACK GUIDANCE AND THE EXTENT OF 34-KT WINDS NORTH OF THE CENTER...THE TROPICAL STORM WATCH REMAINS IN PLACE FOR PART OF THE COAST OF MAINLAND MEXICO. BASED ON THE OFFICIAL FORECAST AND PAST NHC FORECAST ERRORS...THERE IS A 35 TO 40 PERCENT CHANCE OF TROPICAL STORM FORCE WINDS OCCURRING SOMEWHERE IN THE WATCH AREA. DORA COULD ALSO THREATEN THE SOUTHERN BAJA CALIFORNIA PENINSULA IN 60 TO 72 HOURS. FORECAST POSITIONS AND MAX WINDS INIT 20/0900Z 14.1N 101.6W 70 KT 80 MPH 12H 20/1800Z 15.1N 103.5W 85 KT 100 MPH 24H 21/0600Z 16.4N 105.5W 95 KT 110 MPH 36H 21/1800Z 17.5N 107.1W 110 KT 125 MPH 48H 22/0600Z 18.6N 108.4W 105 KT 120 MPH 72H 23/0600Z 20.5N 110.7W 85 KT 100 MPH 96H 24/0600Z 22.5N 113.5W 55 KT 65 MPH 120H 25/0600Z 24.0N 117.0W 30 KT 35 MPH $$ FORECASTER BRENNAN